Warp knit fabric containing loose filling

ABSTRACT

A fabric of the type comprising a plurality of loose filling yarns gathered into generally parallel clusters with a plurality of chains of loops of sewing threads extending along one side of the filling, generally perpendicular to the filling yarns, with sewing thread connecting between loops extending through the filling and along the other side. The loop chains are in sewn bands spaced across the fabric, separated by unsewn bands wherein the loop chains are omitted. At the edges of the unsewn bands, the laterally outermost chain of loops is formed of (a) a first sewing thread which alternately forms loops in the outermost chain and in the chain next to it, and (b) a second sewing thread which only forms loops in the outermost chain alternately with loops formed from the first sewing thread, portions of the second sewing thread connecting between loops being substantially taut against the other side of the filling and in line with the outermost chain of loops.

United States Patent [72] lnventor Ned K. Sharpe FOREIGN PATENTS BurllngtonvN-c- 346,297 4/1931 Great Britain .1 66/192 No :1 374,606 6/1932 Great Britain 66/193 1e 0v. 451 Patented July 13,1971 OTHER REFERENCES {73] Assignee Burlington Industries, Inc. Bahlo, MODERN TEXTILES MAGAZINE, Nov., 1965,

Greensboro NQ pp. 51- 54, copy in 66/85(A).

[54] WARP KNIT FABRIC CONTAINING LOOSE Primary Examiner-Wm. Carter Reynolds Alt0meyCushman, Darby & Cushman ABSTRACT: A fabric of the type comprising a plurality of loose filling yarns gathered into generally parallel clusters with a plurality of chains of loops of sewing threads extending along one side of the filling, generally perpendicular to the filling yarns, with sewing thread connecting between loops extending through the filling and along the other side. The loop chains are in sewn bands spaced across the fabric, separated by un- [56] References Cited sewn bands wherein the loop chains are omitted. At the edges UNITED STATES PATENTS of the unsewn bands, the laterally outermost chain of loops is 3,105,372 10/1963 Whitehead 66/193 formed of (a) a first sewing thread which alternately forms 3,444,707 5/1969 Sharpe 66/193 X loops in the outermost chain and in the chain next to it, and 1,715,482 6/1929 Vorck 66/192 (b) a second sewing thread which only forms loops in the ou- 2,228,944 1/1941 Brandt... 66/193 termost chain alternately with loops formed from the first sew- 2,853,806 9/1958 White 66/193 X ing thread, portions of the second sewing thread connecting 2,890,579 6/1959 Maversberger 66/85 A UX between loops being substantially taut against the other side of 3,389,583 6/1968 Duhl 66/193 the filling and in line with the outermost chain of loops.

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PATENTEUJHLUIQII 3,592,025

' sum u UF 5 INVliN'IUR WARP KNIT FABRIC CONTAINING LOOSE FILLING The present invention relates to an improvement in warp knit fabrics of the type comprising a plurality of loose-filling yarns and thread formed into warp knit chains gathering said filling yarns into a fabric. More specifically, the invention relates to an improvement in which there are bands of parallel sewing thread loop chains, with one or more intervening bands without sewing thread loop chains, the fill yarns extending across said intervening bands.

For purposes of simplicity, the term sewing" will be used herein to refer to the warp-knitting operation. This term has found use in the textile industry in connection with this kind of fabric and avoids confusion because the word warp" is used to refer to another yarn sometimes employed in this type of fabric, as will be explained below. Similarly, for convenience, the threads which form these loops are referred to as sewing thread.

Fabrics of this type can be made by forming a plurality'of chain stitched rows of loops of sewing thread along an array of loose-filling yarn. The stitches pass through the material at spaced points along the machine direction of the fabric and gather the filling yarn into a plurality of clusters separated by spaces corresponding to the stitch insertion points. A plurality of stitches are formed simultaneously across the material, so that the spaces tend to be essentially continuous across the fabric.

ln a preferred form of stitching, the stitches of adjacent chains are interlocked, that is with a tricot stitch. This effect is obtained by the manner in which the sewing thread is supplied to loop-forming needles. The thread passes through guides which oscillate between adjacent needles. Each sewing thread end is alternately supplied to adjacent sewing needles, and each chain contains loops alternately formed from two different threads. I

This type of stitch has several advantages. First, the interknitting of the two sewing ends increases the durability of the fabric. lf simple chain stitching is used, one break in a sewing thread may result in an entire chain of loops being pulled out. In the interlocking stitch described above, each sewing thread is interlocked with two others; therefore, a broken thread will be held by two others.

Another advantage of this type of stitch is that it facilitates the use of warp yarns. It is known that dimensional stability of the fabric can be improved by laying warp yarns against one side of the filling material and fastening them down with sewing thread. ln the interlocking stitch, zigzagging of sewing thread between adjacent chains of loops provides a convenient means for holding the warp yarn in place. The warp yarn is simply laid against the fabric before the sewing thread is moved over it by the sewing thread guide.

In accordance with the present invention, in a fabric of this type, there are bands of sewing thread loop chains, either simple or interlocking, separated by one or more intermediate bands in which sewing thread is omitted. For simplicity, the former will be referred to as sewn bands, and the latter will be referred to as unsewn bands. Generally speaking, the sewn bands have the loop chains approximately equally spaced from each other; the width of the unsewn bands ordinarily is equal to some multiple of the width of the space between adjacent chains in the sewn bands. This arrangement is convenient since ordinary warp-knitting machinery has equally spaced needles, and unsewn bands can be formed by simply not supplying sewing thread to some of the needles.

Adjacent the unsewn bands, it is desirable to assure a neat edge for the sewn bands. This presents certain difficulties when the interlocking chain stitch is used. These are similar to selvedge irregularities described in U.S. Pat. No. 3,444,707. That is, the interlocking chain stitch results in loose threads at the sides of the fabric and at the edge of a sewn band and a rough or irregular edge. This can best be understood by first considering the simple chain stitch. With that type of stitch, the loose-filling yarns are held in clusters by the sewing thread as explained above. On one side of the filling, there is a loop for each stitch, and, on the other side of the filling, there is the sewing thread connecting between adjacent loops. Whereas the connecting thread zigzags between adjacent chains in the interlocking chain stitch, in the simple chain stitch it follows the same line as the loops. Therefore, at the edge of the simple chain-stitched fabric, or the edge of a sewn band in the present invention, the clusters of loose-filling yarns are held together between the loops on one side and the connecting threads on the other side. By cutting the filling close to the last chain of loops, a neat unfrayed edge can be produced.

This cannot be accomplished in the warp-knitting machines which employ the interlocking stitch. In this type of machine, at the edge of the fabric or the edge of a sewn band, two sewing threads form loops in the last chain. The first of these also is formed into loops in-the next to the last chain. The second is used in altemate loops in the last chain. However, when the first thread is transferred to the needle which produces the last chain of loops, the second thread is transferred to the needle which is beyond the last chain. The second thread is formed into a loop by that needle, and then transferred back to the needle which forms the last chain, in time for the next stitch. Since this next needle" is not supplied with sewing thread to form a next stitch," the loop that it has just formed remains loose. Ultimately, it will pull out, leaving loose thread in the last chain of stitches.

This construction has several disadvantages. First, the loose thread in the last chain can result in loosening the entire chain, and is easily snagged. Second, the loose-filling fibers or yarn are not properly held in clusters and give the edge a frayed appearance. Any attempt to trim the fabric close to the last chain of stitches will still leave the filling loose in each cluster.

It might seem possible to simply remove the next needle" so that loose loops will not be formed. However, this is not convenient. For example, needles usually are supplied in sets of, say, 10, mounted on a single lead. It would be very difficult to provide independent mounting of the needles unless they are spaced too far apart. Since a machine is used to produce a variety of widths of fabrics, or to have unsewn bands at various points across the width, it is supplied with needle sets across its full width, and the width of the sewn bands and the overall width of the fabric produced are determined by the number of sewing threads supplied. Therefore, removing the next needle" would require limiting the variety of fabric widths or sewn and unsewn bands to that corresponding to a number of needle sets, or modifying needle sets by removing individual needles. Neither is satisfactory.

As described in the aforesaid U.S. Pat. No. 3,444,707 these difficulties are avoided by pulling out the loose loops before the sewing thread which forms them completes formation of another loop. Therefore, this sewing thread forms alternate loops in the last chain; the portion of that thread connecting between loops follows the chain of loops similar to the thread in simple chain-stitching. This thread, then, tightly binds the clusters of loose filling along a straight line. if the fabric is sheared close to this line, it will have a neat, unfrayed edge. As further described in the aforesaid U.S. Pat. No. 3,444,707, the above-described loose loop is pulled out by a resilient thread guide whose resilience is overcome by yarn tension when the loose loop is formed, but which recovers as soon as the loop is cast off a needle, thereby pulling the loop open.

As used therein, the term resilient is intended to describe a member possessing resilience. The term resilience, for present purposes, refers to the ability of a body to recover its size and shape after being deformed, by stretching, compression or the like. Therefore, the term resilient thread guide refers to a member in contact with the thread which is displaced when a loop is fonned in that thread but which resumes its original position when the loop is castoff.

A suitable source of loose-filling material for use in the present invention is described in U.S. Pat. No. 2,890,579. A plurality of loose-filling yarns are provided from continuous yarns which are wound back and forth across a kind of tenter frame by a carriage, and around heddle hooks on moving conveyor belts at either side of the frame. The conveyors are moving while the carriage traverses the space between them, so that the filling threads are more or less oblique to the machine direction and in two sets which are oblique to each other. That is after a set of parallel threads are caught on the hooks of one of the conveyors, the carriage moves directly across to the other conveyor. While the carriage moves across, the conveyors are moving perpendicularly to the carriage and, by the time the carriage reaches the other conveyor, that other conveyor has moved a short distance. Therefore the heddle hooks on which the threads are caught on the second conveyor are not directly opposite the hooks used on the first conveyor, and the threads are oblique to the machine direction. When the carriage returns to the first conveyor, an opposite effect is observed, and the threads laid down are oblique to the machine direction and to the threads laid down in the previous travdrse. The filling threads are castoff the heddle hooks after they are caught up by loops of sewing threads which gather them into clusters, separated by spaces where the sewing thread passes through the fabric.

Substantially any textile fibers can be used for the wbrp, filling and/or sewing thread in accordance with the present invention. These include natural fibers such as cotton, wool, sisal, linen, jute and silk, manmade fibers and filaments such as regenerated cellulose rayon, polynosic rayon, cellulose esters, e.g. cellulose acetate, cellulose acetate/butyrate and cellulose triacetate and synthetic fibers and filaments such as acrylics, e.g. polyacrylonitrile, modacrylics such as acrylonitrile-vinyl chloride copolymers, polyamides e.g. polyhexamethylene adipamide (nylon 66), polycaproamide (nylon 6) and polyundecanoamide (nylon ll), polyolefin, e.g. polyethylene and polypropylene, polyester, e.g. polyethylene terephthalate, rubber and synthetic rubber, saran, glass, and the like. Sewing yarn sizes ordinarily are 15 to 1,100 denier and filling yarns 15 to 3,300 denier. When warp yarns are used, they may be, e.g. 15 to 6,600 denier. Normally, stitches will be 0.4 to 4 mm. apart along the warp and about l.l3 to 3.57 mm. apart across the fabric. Typically, the sewn fabric weighs 2 to 35 ounces per square yard.

The invention will be better understood from the following detailed description of preferred embodiments, reference being made to the drawing, in which:

FIG. I is a front view of a fabric according to the present in vention,

FIG. 2 is a perspective view of a part of the apparatus used to manufacture the fabric.

FIG. 3 is a plan view, partially schematic, of the apparatus of FIG. 2;

FIGS. 4 and 5 are side views, partly in section, showing a portion of the apparatus of FIG. 2 in which stitches are formed;

FIGS. 6 and 7 are perspective views of a portion of the apparatus of FIG. 2 showing the mechanism used to assure neat edges for sewn bands in the fabric;

FIG. 8 is a vertical section through the apparatus;

FIG. 9 is a horizontal section through the apparatus; and

FIG. 10 is a schematic view showing the path of movement of thread guides.

As seen in FIG. 1, the sewing thread in the fabric is formed into interlocked chain-stitching substantially along the warp or machine direction. Each sewing thread I is formed into a plurality of loops 2 spaced along the length of the fabric, each loop passing through the fabric. The loops are formed into parallel chains, but each chain is formed from two threads which alternately are formed into stitches of adjacent chains. For example, one chain of loops, designated 3 in the drawing, is formed from two threads 4 and 5. A first loop 6 is formed from thread 4, the next loop 7 is formed from thread 5 and the next loop 5 is formed again from thread 4, etc. Thread 4 also is formed into loops 9 in the chain W on one side of chain 3,

in a chain 12 on the other side of chain 3, alongside loops 6 and 8 in chain 3. The arrangement is such that each sewing thread is interlocked with two others in adjacent stitch lines so that, if a thread breaks, it will not pull out a succession of stitches as it would if each chain were formed from a single thread.

The formation of this chain-stitching is illustrated in FIGS. 4 and 5. A needle 20 is provided which has a point 21 at one end and a hook 22 adjacent the end. There is a groove 23 in the upper surface of the needle in which slides part of a bent wire latch 24. The needle is mounted for horizontal reciprocating motion.

A web 25 moves downwardly across the path of the needle,

and as the needle reciprocates it alternately pierces and is withdrawn from the web, the web being advanced downwardly while the needle is withdrawn.

A thread guide 26 is provided to insert the sewing thread 27 into the hook 22 when the needle extends through the web. As can be seen by comparing FIGS. 4 and 5, the thread guide moves up alongside the needle, across it and down on the opposite side, laying the thread in the hook 22 as it moves across. Then the needle is retracted and the latch 24 moves across the hook. At the same time, the web 25 moves down past the needle. As the needle moves forward to receive sewing thread again, the thread previously placed in the hook slides back onto the shank of the needle as seen at 28 to form a loop 29. When the needle retracts again and the latch 24 closes, the loop 29 slides forward toward the tip of the needle, pushed if necessary by the upright portion of latch 24. Since the hook 22 is closed by the latch, the loop 29 slides over the hook and is castoff the point 21 of the needle. At the same time, the thread in the hook is pulled through loop 29.

The thread guide 26 is mounted to alternately move up and across two needles, designated 30 and 31 in FIG. 10. Therefore, it describes a figure eight path 32.

For rapid machine operation, it is advisable to use circular eccentric cams for actuating the needles and the thread guides. As shown in FIG. 9, a needle bar 33 carrying the needles 20 is actuated by a connecting rod 34 extending from an eccentric rod 35 linked by a strap 36 of an eccentric cam 37 which is rotated by the motor-driven shaft 35 supported by a housing 39. Similarly, the reciprocating movement of the latches 24 required for closing the hooks of the needles is obtained by means of an eccentric cam 40 cooperating with a strap 41 actuating, through an eccentric rod 42 a connecting rod 43 that actuates the brackets to which the latches 24 are attached through a cam. The holders of the thread guides 26 are fastened to a guide bar 44 which, by means of suitably attached lever arms 45, is fixedly mounted on a shaft 46. This shaft, being rotatably mounted within bearings 47, is adapted to slide longitudinally back and forth and carries a short lever 48.

Lever 48 is connected with a coupling rod 49 linked to an eccentric rod 50. Rod 50 with its strap 51 encloses the eccentric cam 52 which, by means of an intermediate connecting rod 53, moves the thread guides up and down. Aside from this reciprocating movement, the thread guides must undergo an axially transverse back and forth movement in order to insert threads into the hooks of the needles and to alternate between needles. For this purpose, the thread guides 26 and the shaft 46 carrying the same are operated to perform one complete back and forth movement while the needles are moved twice in and out. To accomplish this, a pinion 54 keyed to the shaft 38 engages a spur wheel 55 of twice its size. Consequently, the spur wheel rotates at half of the speed of the shaft 38.

Spur wheel 55 is fixedly connected with an eccentric cam 56 whose strap member 57 is linked by an eccentric rod 55 to a connecting rod 59 axially slidable in a bearing 60. When in operation, the rod 59 and its linkage 6ll impart axial reciprocation to the shaft 46 by actuating an angle lever 62 rotatably mounted to a pivot 63. The tension spring 64 fastened about the shaft 46, between one of the bearings 47 and the adjacent lever arm 45 of the guide bar 44 aids the axially oscillating movement by forcing the shaft against an adjusting screw 65 connecting the free end of angle lever 62 to that of the shaft 46.

The filling yarn supply is illustrated in FIG. 3. At opposite sides of the apparatus, there are chains 67 and 68, each trained around sprocket wheels and driven by a motor, not shown. On each of the chains 67 and 68 there are a plurality of upright heddle hooks around which the yarn is wound. Filling yarn is laid in place by a yarn guide mounted on a mobile carriage 70 which is traversed back and forth above the chains 67 and 68. The arrangement is such that as the carriage moves a bit past the hooks on one side of the chains, the chain moves and the yarn is turned around one or more hooks. Then the carriage moves in the opposite direction across to the other chain and past that chain so that the procedure is repeated.

In actual practice, the carriage 70 carries several yarn guides and a plurality of yarn ends is laid down as superimposed layers, each layer being at an angle to the layer next to it. The filling yarn remains in this position until loops are formed by the sewing operation, and the filling is cast off the chains 67 and 68. Then the filling takes the form of generally parallel clusters of yarn separated by spaces at sewing thread stitch insertion points. i

In some cases, the fabric may use warp yarn which is simply laid under the sewing thread and against the filling. The warp yarn 71 is supplied downwardly against the filling through a yarn guide 72 as seen in FIG. 2.

As explained in the aforesaid U.S. Pat. No. 3,444,707, a special arrangement must be provided for supplying the sewing thread. In the conventional machine described previously, a single sewing yarn package supplies a plurality of ends, one for each thread guide. However, in using a spring device to avoid loose loops, this is not possible because the sewing thread at the edge of a sewn band forms only one half as many loops as threads forming loops at the interior of the fabric. To

maintain proper tension, it is necessary that the outermost sewing thread not unwind from the package at the same rate as other threads. Therefore, the outermost sewing thread is supplied from a separate package, capable of unwinding at a different speed from thread used at the interior of the package. The arrangement is illustrated in FIG. 3 in which several sewing yarn packages are indicated by the numerals 73 and 74 on a beam 75. Sewing thread ends are supplied from these packages through appropriate thread guides and ten-. sioning devices, not shown, to the thread guides 26 which lay them into the sewing needles 20. The packages 73 each supply one end to a thread guide at the edge of a sewn band while the packages 74 supply a plurality of ends to the other thread guides 20. All three packages are mounted on the beam 75 to be capable of rotation at separate speeds. If the packages 73 are mounted to the beam and the beam is rotatable, the packages 74 must be mounted on the beam with hearings to rotate independently. If the packages are unwound by a power drive, rather than through thread tension, obviously packages 73 must be driven at slower speed than-the package 74, i.e. at about half speed.

The role of the loop-pulling mechanism used for neat edges for sewn bands can best be understood from FIGS. 2, 6, 7 and 10. Assuming that a needle is the needle at the edge of a sewn band, one thread guide designated 76 (see FIG. 1) describes the path 32 and alternately lays thread into needles 30 and 31. An adjacent thread guide 78 alternately lays thread in needle 31 and the needle 79 which is adjacent to needle 31. Thus, when the thread guide 76 is laying thread into needle 30, thread guide 78 is laying thread into needle 31 When the next stitch is formed, thread guides 76 and 78 lay thread into needles 31 and 79, respectively. But no thread is laid into needle 30. Therefore, when needle 30 is retracted, the loop on its shank is castoff, but there is no thread in its hook to pull through the loop. Therefore, that loop is left loose.

To prevent this, means are provided for pulling out that loop before. another loop is formed by needle 30, so that the thread is pulled ti ht behind the line of loops formed by needle 31. As seen in GS. 2, 6 and 7, this is accomplished by a resilient thread guide 80 over which passes the thread supplied to the thread guide 76. The resilient thread guide 80 is a piece of spring steel, firmly mounted at one end to the frame of the apparatus, for example by a block 81. The free end of the resilient thread guide 80 is bent to form a kind of hook 82 over which the sewing thread passes. There also is a single loop 83 formed in the wire between its ends, to give it controlled resilience. The resilience of the guide 80 is sufficiently weak to be overcome by thread tension when a loop is formed by needle 30, but sufiiciently strong to pull out a loose loop of thread after it is cast off the needle 30. Thus, when a loop is formed on needle 30, the thread pulls the guide 80 down, and when the loop is castoff and is loose, the guide 80 elevates and pulls out the loose loop. This sequence is illustrated diagrammatically in FIGS. 6 and 7.

In the embodiment shown in the drawings, there is a single unsewn band separated by two sewn bands, and the abovedescribed loop-pulling technique is used at both sides of the -unsewn band. Of course, a simple chain stitching can be used in either band, avoiding the need for the loop-pulling equipment, but the fabrics would then be subject to the difficulties mentioned previously.

More than one unsewn band may be used and the widths of the sewn and unsewn bands may be varied as desired.

The completed fabrics may be overcoated with foam, as

described in the copending application of Robert L. Jones and Robert E. Provost, Ser. No. 681,703 filed Nov. 9, 1967. The fabrics so coated will have interesting ornamental characteristics, since, in the unsewn bands, the fill yarns will not be gathered into clusters. The fabrics, especially without the foam backing, have many advantages. For example, the open bands are easily slit lengthwise, providing a convenient way to produce several strips of narrow fabric, which may be formed into yamlike material for use in making special purpose fabrics. In addition, the fabric will have increased ability to be twisted and to conform to irregular shapes without bulging or wrinkling.

Various changes may be made in details of construction and mode of operation without departing from the scope of the invention, as defined in the appended claims.

I claim:

1. A fabric having a filling comprising a plurality of filling yarns gathered into generally parallel clusters said clusters being secured together by threads formed into a plurality of sewn bands each comprising a plurality of chains of loops of sewing threads extending along one side of said filling generally perpendicular to said filling yarns with sewing thread connected between loops extending through said filling and along the other side of said filling,

the sewing threads in said fabric alternately forming loops in adjacent chains and each chain containing loops altemately formed of two different sewing threads,

and such sewn bands being separated by at least one unsewn band not containing said loop chain but the filling yarn extending across said unsewn band,

a laterally outermost chain of loops in a sewn band, adjacent an unsewn band, being formed of a. a first sewing thread which alternately forms loops in said outermost chain and in the chain in said sewn band next to it and b. a second sewing thread which only forms loops in said outermost chain alternately with loops formed from said first sewing thread and p the portions of said second sewing thread connecting between loops being substantially taut against said other side of said filling and substantially in line with said outermost chain of loops. 

1. A fabric having a filling comprising a plurality of filling yarns gathered into generally parallel clusters said clusters being secured together by threads formed into a plurality of sewn bands each comprising a plurality of chains of loops of sewing threads extending along one side of said filling generally perpendicular to said filling yarns with sewing thread connected between loops extending through said filling and along the other side of said filling, the sewing threads in said fabric alternately forming loops in adjacent chains and each chain containing loops alternately formed of two different sewing threads, and such sewn bands being separated by at least one unsewn band not containing said loop chain but the filling yarn extending across said unsewn band, a laterally outermost chain of loops in a sewn band, adjacent an unsewn band, being formed of a. a first sewing thread which alternately forms loops in said outermost chain and in the chain in said sewn band next to it and b. a second sewing thread which only forms loops in said outermost chain alternately with loops formed from said first sewing thread and the portions of said second sewing thread connecting between loops being substantially taut against said other side of said filling and substantially in line with said outermost chain of loops. 